Asexual propagation for plants has been shown for some species to yield large numbers of genetically identical embryos, each having the capacity to develop into a normal plant. Such embryos must usually be further cultured under laboratory conditions until they reach an autotrophic “seedling” state characterized by an ability to produce their own food via photosynthesis, resist desiccation, produce roots able to penetrate soil, and fend off soil microorganisms. Some researchers have experimented with the production of artificial seeds, known as manufactured seeds, in which individual plant somatic or zygotic embryos are encapsulated in a seed coat. Examples of such manufactured seeds are disclosed in U.S. Pat. No. 5,701,699, issued to Carlson et al., the disclosure of which is hereby expressly incorporated by reference.
Typical manufactured seeds include a seed shell, synthetic gametophyte and a plant embryo. A manufactured seed that does not include the plant embryo is known in the art as a “seed blank.” The seed blank typically is a cylindrical capsule having a closed end and an open end. The synthetic gametophyte is placed within the seed shell to substantially fill the interior of the seed shell. A longitudinally extending hard porous insert, commonly known as a cotyledon restraint, may be centrally located within the synthetic gametophyte and includes a centrally located cavity extending partially through the length of the cotyledon restraint. The cavity is sized to receive the plant embryo therein. The well-known plant embryo includes a radicle end and a cotyledon end. The plant embryo is deposited within the cavity of the cotyledon restraint cotyledon end first and is sealed within the seed blank by at least one end seal. There is a weakened spot in the end seal to allow the radicle end of the embryo to penetrate the end seal.
Currently, the seed shell is manufactured by hand and is formed from sectioning a tube, such as a straw, and processing the sections of the tube to enhance its abilities to withstand exposure to the environment. One such seed shell is manufactured by sectioning a straw of fibrous material, and then coating the resulting straw section with a wax. One suitable method for applying the wax coating is to dip the straw sections into a bath of wax. The straw sections are then withdrawn from the wax bath and then the wax is permitted to harden to seal the straw sections.
Although such seed blanks are effective, they are not without their problems. As a non-limiting example, because the current process of manufacturing seed blanks is manual, it is labor-intensive and, therefore, expensive. Additionally, because such existing processes are manual, manipulation and manufacture of a large number of seed blanks in accordance with existing practice can be time-intensive. As a result, mass production of manufactured seeds is not only time-consuming, but also expensive.
Thus, there exists a need for a method and system of manufacturing artificial seed blanks that can manipulate and assemble a large number of seed blanks at a relatively low cost, with a high degree of reliability, and without adversely affecting the quality of resulting seed blanks.